JP3498850B2 - Metallic coating composition and coating film forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a metallic coating composition and a method for forming a coating film.

[0002]

2. Description of the Related Art It has been conventionally known in the automobile industry to use a metallic coating composition containing a metal powder pigment.

In a coating film using the metallic coating composition, a coating film having a large so-called flip-flop effect (metallic feeling), which makes the reflection effect of light rays different depending on the angle at which the coating product is viewed, is excellent in cosmetics. Development is required from the field.

[0004] As a method of forming a coating film having an excellent metallic feel, it is generally known to add silica powder, polymer fine particles and the like to a metallic paint composition. The reality is that we have not obtained anything to satisfy.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have used barium sulfate fine particles and polymer fine particles in combination with conventional metallic coating compositions. By this, a metallic feeling,
The inventors have found that the coating composition can provide a coating film having excellent gloss, and completed the present invention.

That is, the present invention provides a metallic coating composition with transparent barium sulfate fine particles having a primary particle size of 0.1 μm or less in an amount of 5 to 50 parts by weight and a particle size of 100 parts by weight of a resin component.
Metallic coating composition containing 1 to 30 parts by weight of O. 5 μm or less polymer fine particles to 100 parts by weight of resin component
And the baked coating film formed from the coating composition is milk.
After applying the metallic coating composition to a metallic coating composition and a material characterized by not having a white color , followed by applying a clear coating composition to form a two-layer coating film, both coating films It is a coating film formation method that is cured at the same time.
And the baked coating film formed does not have milky white color.

In the coating composition of the present invention, the metallic coating composition used to contain the barium sulfate fine particles and the polymer fine particles is a known composition having a metallic pigment and a crosslinkable curable resin composition as main components. Is. Specifically, examples of the metallic pigment include aluminum powder, copper powder, mica powder, mica-like powder coated with titanium oxide, MIO (mica-like iron oxide), and the like, and examples of the crosslinkable curable resin composition include A thermosetting resin composition comprising a base resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin and a urethane resin and a cross-linking agent (amino resin, blocked polyisocyanate compound, etc.) or a polyisocyanate compound for the base resin. Examples thereof include a resin composition that is crosslinked by heating at room temperature or low temperature (about 100 ° C. or lower), which is obtained by adding a curing agent such as A resin that does not undergo a crosslinking and curing reaction, such as a cellulose acetate butyrate resin, may be further added to these resin compositions. The type of the metallic coating composition may be any of a solution type coating using an organic solvent as a medium, a non-aqueous dispersion coating and a multi-component coating, and a water-based coating containing a water-soluble resin and / or a water emulsion resin as a main component. Type may be used. Coloring pigments, extender pigments, various additives, and the like can be optionally added to these metallic coating compositions.

The barium sulfate fine particles used in the coating composition of the present invention are transparent pigments containing barium sulfate as a main component and have a primary fine particle diameter of about 0.1 μm or less, preferably about 0.02 to 0.08 μm. Good in the range. If the primary particle size exceeds about 0.1 μm, the metal powder pigment in the coating composition tends to move and a coating film with less metallic appearance is formed, which is not preferable.

Typical examples of the barium sulfate fine particles include, for example, Varifine BF-1, Same as left BF-10, Same as left BF-20 (above, trade name of Sakai Chemical Industry Co., Ltd.). Can be mentioned.

The content ratio of the barium sulfate fine particles is
The amount may be about 5 to 50 parts by weight, preferably about 10 to 30 parts by weight, based on 100 parts by weight of the resin component in the metallic coating composition. If the content of fine particles of barium sulfate is less than about 5 parts by weight, the metal powder pigment in the coating composition will move easily to form a coating film with less metallic feel. On the other hand, if the content exceeds about 50 parts by weight, gloss and It is not preferable because a coating film having poor performance is formed.

The polymer fine particles used in the coating composition of the present invention are insoluble in the resin and solvent in the metallic base coating composition and have a particle size of about 0.5 μm or less, preferably about 0.01 to 0.3 μm, More preferably from about 0.05
A range of 0.1 μm is good.

The composition of the polymer fine particles is not particularly limited, but two or more radically polymerizable unsaturated groups in a molecule capable of forming a coating film excellent in metallic feeling in combination with the barium sulfate fine particle component. It is desirable to use the gelled polymer fine particles obtained by emulsion-polymerizing a polymerizable monomer having ## STR3 ## and a radically polymerizable unsaturated monomer other than the monomer in the presence of a reactive emulsifier having an allyl group in the molecule. For details of the gelled polymer fine particles,
Since it is described in the specification of Japanese Patent Laid-Open No. 3-66770, the detailed description will be replaced with this reference.

The content of the polymer fine particles is about 1 to 100 parts by weight of the resin component in the metallic coating composition.
30 parts by weight, preferably about 3 to 15 parts by weight. When the content ratio of the polymer fine particles is less than about 1 part by weight, the metal powder pigment in the coating composition tends to move and a coating film with less metallic feeling is formed. On the other hand, when the content ratio exceeds about 30 parts by weight, gloss and It is not preferable because a coating film having poor performance is formed.

The coating composition of the present invention may contain an antifoaming agent, an antifungal agent, an extender pigment other than the above, an ultraviolet absorber and an organic solvent, if necessary.

Next, a method for forming a coating film using the coating composition of the present invention will be described below. The method of the present invention specifically comprises applying the metallic coating composition to the surface of the material to form a metallic base coat, and subsequently applying the clear coating composition to the surface of the obtained base coat to form a metallic base coat and a clear coat. It can be carried out by forming a two-layer coating film and then simultaneously curing both coating films by heating.

As the above-mentioned material, there can be used, for example, a car body which has been subjected to a chemical conversion treatment, on which an electrodeposition cured coating film and an intermediate coating cured coating film are formed. The metallic and clear coating compositions can be applied by a conventional coating method, for example, electrostatic coating or non-electrostatic coating. The thickness of the metallic base coat after curing is approximately 5 to 30 μm
Is preferred. After applying the metallic coating composition, it is left at room temperature for several minutes or pre-dried at about 50-80 ° C for several minutes, and then the clear coating composition is applied. As the clear coating composition, conventionally known compositions can be used without particular limitation, but acrylic / melamine-curable organic solvent type coating compositions are preferred. The thickness of the clear coat after curing is preferably about 20 to 80 μm. The heating for curing both coating films is usually performed at about 120 to 180 ° C for about 30 to 90 minutes.

[0017]

EXAMPLES Next, the present invention will be specifically described with reference to examples. All parts and% are by weight.

Production Example of Polymer Fine Particles 1 equipped with a stirrer, thermometer, cooling tube and heating mantle
In a liter flask, 3536.5 parts of deionized water and a sulfosuccinic acid-based acrylic group-containing anionic reactive emulsifier (Sanyo Kasei "Eleminol JS-2" 39% aqueous solution)
51 parts of an emulsifier was added, and the temperature was raised to 90 ° C. with stirring. 2,2'-azobis "2-methyl-N- (2
-Hydroxyethyl) -propionamide polymerization initiator 1
20 parts of an aqueous solution prepared by dissolving 2.5 parts in 500 parts of deionized water
% Was added. After 15 minutes the monomer mixture (styrene 46
5 parts of 0 parts, 460 parts of n-butyl acrylate, 60 parts of 1,6-hexanediol diacrylate and 20 parts of hydroxyethyl acrylate) were added. Then, after stirring for another 30 minutes, dropping of the remaining monomer mixture and polymerization initiator was started. The dropping of the monomer mixture was carried out for 3 hours, and the dropping of the polymerization initiator was carried out over 3.5 hours, during which the polymerization temperature was kept at 90 ° C. After the addition of the aqueous solution of the polymerization initiator was completed, the mixture was heated for 30 minutes, kept at 90 ° C., cooled to room temperature, and taken out using a filter cloth to obtain an aqueous gelled fine particle polymer aqueous dispersion having a solid content of 20%.

Each of these aqueous dispersions was dried on a stainless steel vat in an electric hot air dryer at 60 ° C. and taken out as a solid resin. Then, the mixture was dispersed in a mixed solvent of xylene / n-butyl alcohol = 50/50 (weight ratio) heated to 60 ° C. to prepare gelled fine particle polymer dispersions having a solid content concentration of 20%. The particle size of the dispersion is about 0.08 μm (Nanosider N Coulter, Inc.
-4).

Production Example of Acrylic Resin Solution 40 parts of cellosolve acetate was charged into a usual acrylic resin reactor equipped with a stirrer, a thermometer, a reflux condenser, etc., and the mixture was heated and stirred.
After the temperature reached 5 ° C, the following monomer-polymerization initiator mixture was added over 3 hours. Styrene 10 parts Isobutyl methacrylate 30 parts n-Butyl methacrylate 12 parts 2-Ethylhexyl methacrylate 20 parts 2-Hydroxyethyl methacrylate 25 parts Methacrylic acid 3 parts Cellosolve acetate 50 parts α, α′-azobisisobutyronitrile 4 parts

1 hour after the above mixture was added, the reaction was carried out for 135 hours.
Continue at ℃, then 10 parts cellosolve acetate,
A mixture of 0.6 parts of α, α'-azobisisobutyronitrile was added over 1 hour 30 minutes. Then 2
After reacting for a time, the cellosolve acetate was distilled off under reduced pressure to adjust the resin concentration to 65%, and the Gardner viscosity Z (2
A 5 ° C.) acrylic resin solution was prepared.

Production Example of Pigment Paste 154 parts of the 65% acrylic resin solution, Varifine B
F-20 (Sakai Chemical Industry, trade name, primary particle size about 0.03
μm, barium sulfate powder) 200 parts and xylene 146
Part of the mixture was dispersed by a shaker disperser to obtain a pigment paste having a solid content of 60%.

Examples and Comparative Examples The formulations shown in Table 1 were dispersed with a Despar disperser to obtain coating compositions of Examples and Comparative Examples. The compounding amounts in Table 1 are all parts. In addition, Uban 20SE in Table 1
Is a butylated melamine resin manufactured by Mitsui Toatsu Co., Ltd., having a solid content of 60%, and Alpaste # 491.
9 is manufactured by Toyo Aluminum Co., Ltd., trade name, solid content 65
%.

Formation of Metallic Coatings Using the Coating Compositions of Examples and Comparative Examples Epoxy cationic electrodeposition coatings were dried to a coating thickness of about 20 μm on 0.8 mm thick dull steel sheets which had been subjected to zinc phosphate conversion treatment. After electrodeposition coating and baking at 170 ° C for 20 minutes #
Sharpen with 400 sandpaper and wipe with petroleum benzine to degrease. Then, an intermediate coating surfacer for automobiles was air-spray coated to a dry coating film thickness of about 25 μm.
After baking at 0 ° C. for 80 minutes, it is sanded with # 400 sandpaper, drained and dried. Next, degrease with petroleum benzine and use it as a material for testing.

Next, the metallic base coating composition of each of the examples and comparative examples was applied onto the prepared material by an air spray coating machine so that the dry film thickness was about 10 μm, and the coating was performed at about 80 ° C. After preliminary drying for about 10 minutes, Magicron # 1000 clear (trade name, acrylic melamine type organic solvent type paint, manufactured by Kansai Paint Co., Ltd.) was applied so that the dry film thickness was about 40 μm. After setting at room temperature, heating was performed at 140 ° C. for 30 minutes to obtain a metallic coating film. The results of examining the appearance of these coating films are shown in Table 1. The appearance of the coating film in Table 1 was evaluated based on the following criteria.

Flip-flop property: the result of visual evaluation of the coated surface. ⊚: Metallic powder is oriented parallel and evenly with respect to the coated surface and has a good metallic feeling. ◯: The metallic powder is oriented slightly obliquely to the coated surface, and the metallic feeling is slightly inferior. B: The metallic powder is oriented obliquely with respect to the coated surface and the metallic feeling is poor. X: The metallic powder is oriented obliquely with respect to the coated surface and the metallic feeling is remarkably poor. Metallic unevenness: the result of visually judging the coated surface.
⊚: Metallic powder is oriented parallel and uniformly to the coated surface, and no metallic unevenness is observed.
○: Some occurrence of metallic unevenness is recognized. △;
The occurrence of metallic unevenness. X: Metallic unevenness is remarkably observed. Gloss: A value obtained by measuring the specular reflectance of 60 degrees.

[0027]

[Table 1]

[0028]

Since the coating composition of the present invention has the above-mentioned composition, it is particularly excellent in the appearance of the coating film (flip-flop property, metal unevenness, gloss, etc.).

Continued front page       (56) References JP-A-56-76447 (JP, A)                 JP-A-62-87286 (JP, A)                 JP-A-53-49025 (JP, A)                 JP 60-149674 (JP, A)                 JP-A-57-7827 (JP, A)                 JP-A-3-66770 (JP, A)                 JP 58-129065 (JP, A)                 JP-A-53-133233 (JP, A)                 US Patent 4753829 (US, A)

Claims (2)

(57) [Claims] 1. A metallic coating composition having a primary particle size of 0.
1 to 30 parts by weight of transparent barium sulfate fine particles of 1 μm or less with respect to 100 parts by weight of the resin component and 1 to 30 parts by weight of polymer fine particles having a particle diameter of 0.5 μm or less with respect to 100 parts by weight of the resin component. A metallic coating composition comprising:
A metallic coating composition characterized in that a baked coating film formed from the product does not have a milky white color . Wherein applying a metallic coating composition according to claim 1, wherein the material, followed after having formed the coating to 2-layer coating film of the clear coating composition, obtained by curing the Ryonurimaku simultaneously
A method of forming a coating film, in which the baked coating film formed is milky white
A method for forming a coating film, characterized in that